Firing circuit



Sept 29, 1959 R. MoRlsoN ETAL 2,906,206

FIRING CIRCUIT Filed Sept. 13, 1946 F I6. l.

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2a IlIlliwllllllw'l'llilllll l INVENToRs Romer MoH/30N hjj//f//f/f/f/// waan-n ma. Rose-nrs 'MM BY y v ATTORNEY il, -n

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milled States Patent EIRINGCIRClIIT 'Rodney rMorison, iUnited l States rNavfy, '.Basadena,

-and Walter Y:van sBeRoherts-1rinceton,NJ.,; assignors toathe tUnited States cf Americans-represented .hr`v the SecretarycoftheNmy Y Applicationseptember c13,1946;'S e1'i al-'l`10. 696,948

'3 Claims .r-(Cl- 1192-70@ This: invention relates :generally-toi circuits i for ipredectermining ithe'time cofcdetonation of fan-rdnancmissile having; an electrical `igniter. xMoreftspeciically,,1 ityrelates tozcircuits zoffthegeneral: tvpeincludinguan electron-.wheat ratronv is;representative,:andsmeans fonpredetermining 20 the time fof-,discharge of1the::t11bethe; ringiinrgturn `serving to actuateian; electrical: igniter. iThe:i predeterminingfcir cuit is anovel 'anrl irnprovrml'membercof` the .generfakclass which comprises fresistors, fcondensers and 0a :source .of .volt-age, :thecondensersmeing chargedzthrough .certainfof `the resistors :at a :controlled rate :and adischarging.; at ,fthe 1properztimeeto-: energize the-,zelectiicah igniter.

- One jforineofzthe :noveltcircuit ,includes AJa neonfglow- '.lamp for :equivalent .cold #electrode ,tube :containing ra monatomic tgas; at :low pressure iin '.the :discharge device vinputgcircuit, whilezanother fornurelies tsolelyv ontresistors While :the s invention yis not limited; to i any Lspecicfcircuit fdimensions, theparameters-K hereinbelowcset: forthA in parenthesesrhave heenv found practicable in: onetsuccessul embodiment of the invention and are suggested forfpur-"I iposeszof illustration.

IForzaibetterfand furtherunderstandingrof the invention together `'with lother andifnrtherV objectsLthereofareference is made tofthe followingdescription;taken in: conjunction witl1 the; appended-.claims and the taccompanyingfnaw? ings in which:

`Fig. :1 is, aicircuit diagram of a:ringcircuitzinaccord- -ance withxthe invention-including argaseglowttubeimthe fFigure 2, is anrnodied' formtof tiring;-circuitiintaccordancey with :the invent-ion ibut-l in^-rvvhichno :glowlamp Jis employed; and

'.Fig.` 3 v3is;a:fragmentary sectional-.viewsoffthefnose of va projectile;showingfschematically-themeans ofi-initiating the vfuze,.-action;.upon setbacktproducedbytiring-ofthe projectile.

.ReferringfnowaspecicallyttotFig. fLfthetcircuit therein represented 4comprises .lafidirecti currentsource 1.0, o'frelavtively; high voltage, savofthezorder ofsonelhundred volts, the positive terminaLof Whichisl connected-#through a switch 11 andu a ,resistor 12 (2 megohms) xto the plate of a Thyratron V-]&4,andthe-negativeterminal of which is connected, togthe gridfoftthe fhyratron through a resistor` 15 (l megohm).

`Bridged acrossbattery 10, beyondthe switch r11, .is a seriescircuit comprising a,c.ondcnser16 (1 microfarfad) and avariable resistor 17 offIhQOILdercof 4 megohms) in series. Condenser 16 charges fromtsource lgthrouglrresistor 17. .Preferably resistor 17`is,con,siderablyhigher in resistancethan resistor 12.

Connected acrnssondenser,,16.,iscanother series combination, comprising, a resistorjIS (1 megohrn.)I and a Aneon-glow-llampr-I. v-Theelectrodes of lamp" "18 are normally maintained at the same potential difference as that prevailing between the terminals of condenser 16,

Y I2 since fnormal-ly there is substantially no Acurrent flow @through resistorflS and thereforegno voltage drop;therein. :zMoreoveLJhe :grid o'fLthel ,"lrhyratrcuf y.isqricirrnally at v:the samefpotential with respect toA the; cathode asv-is the respect tov theA grid may -f beradiusted: byimoveble connec- 1tion'l9,nsliiftable;to;y -theproper :point toLpwVide-,Whatever snegative ,gridirbias :may fheadesired.

- .15A vworkK :ircuit consist-ingrof anfelectrical ,ignitergor :tiringtsqnibi znfandfa. second ,cendensenzl i ltmicrofarad) in series, fis coupled :tot the r Qathodefanode; circuit ,of the ltrmilzzbetunderstoodby thosezaskilledfin :the ordnance artathateariiringsquib: orelectricall igniter -conventionally comprises ahigh lresistance wircrimbedded. ini/,sometimiilammable chemical .snhstance .and ,has `such operation rthatewhenzthei wire; is heatedf the-:substance: is l ignited and the missile, in which the circuit is installedtortin conmectionzwvithwwhich x the ;.circuit is operative; is r detonated. .3 showstafmeans tof initiatingthe uze iaction. Ihm-,fuzecircuits acerinopenativefbefore Ltirin'g't-sincebroth gtheenputftand workgcircuits varefconnected:to thefpositive 5-xterrninal ofbatteryztl throughxfswitch 11,L whiohi-is ini- ,ztillyr open. weightiis iattached= to :the Ydisplaceable tienduoff switchfll. V-"\\.hen; the projectileSiisfhred in the anirection indicated by V:the garrow, r.set, back :forces act vi:upon:tvveightiS-:totcause;the clnsuref switch 11. "The rringrcircuitiisithen innaneeperable:condition .and the i timing-action commences.

Y y Themperatiomof thecircuitashown inFig. `l1 will now ,sbefrdescrihed. ,"tWhenfswitch 1-1 :is closed l'by .set fbaok .-,ioroes iupon filing, :two signicant ,phenomena occur. Condenser/121 :,acquires la charge :from lthe z-zvbattery :at a .f1-tate controlled by its4 -capacitance and by f the .resista-nce `,andthe chargingrpath including 4 resistor 12, the. charging v zwi-Arent, h0wever, l always ubeing insucienb4 to ignite -the nigniterthroughcwhichtitflows. fAt thetsameltime, ycon- 40 fdenseralialso,acquires :aechargeifromsource ^I() through iresistorrll The circuits `are `so .arranged i that ;the t time cQOIlSftant of the circuit comprising felements j 10, :16, 117 fris fgleater than rthat of 'the lfcircuit.- comprising elements 210312,;21, 20, so that;crondenser.1t6;charges more ,slowly -than condenserl. hisfisiasdesiredresult, as condenser 221 should besuhstantiallyffu-lly chargedbeforef'the volt- .;ageiacross condenser lthas :becometsufdcientlyJ high z to ,tcauseglamp x18; to' `llash :and1 tube: 1.4 to re.

Ultimately'a ,.glowedischarge in lamp `'18 Ytakes place,

resulting in La. drop t of the.; impedance :of the; lamp. tdown to its breakdown Value and apartialfdischargefof ,ccn- Ltdrelleer,tltthrough lamp 18,3and resistor 115,;'downfto a nvelt-agegnear the ;extim:,tionv voltage 1 of ;the lamp. fLamp fisga Onlinear ,impcdaneezswh-,ile resistor :l5 ds-linear.

:,'Ihelowf ofmrent-,duriiig -the-L ashngtofylarnp 18 prod,uces;a .voltage dropfacross resistonlSwhich:reduces the negatiyegbiasnnftheggrdof the Thyratron totsuchqan ,extent -thatit ,becomes lcondu,ctive,.`tl1e Aelectron ilowbeing from` ``thenegatively charged ,plates of ,condenser v,16,

y"through resistor 15 tothe junction ofgresistorvlandgthe L"ThyratrcuA grid, and thus beingjngsuch a directionas -to-render the Thyratron grid morepositive.

J(Phe Thyratron Adischarge current rcomes 'from "con- Vdenser-121, uwhich discharges vthrough the plate-cathode circuit of the Thyratron andrigzniterjz, the

fllatter.

j r*'lhfe secondicircuit 'illustrated schematically vin Fig.

'+2 -cornprises a vnumber lof circuit elements -likek in strut:-

turend-'unction-'to those represented'inFigl and which bear like reference numerals, and similar elements which have like reference numerals primed. It comprises a source of voltage k (100 Volts), the negative terminalV The connection of the negative terminal of source 10 to the Thyratron grid, through resistor 15, causes a iixed but adjustable negative bias to be impressed theref on.V The positive terminal of source 10 is connected through switch 11 to a charging circuit comprising resistor 17 V(5 megohms) and condenser 16 (1 microfarad), the remote terminal Vof the latter being connected to the negative terminal of source 10. Condenser 16Vis also provided with a discharge path comprising resistor (l megohm) and resistor 18' (10 megohms). It will be Y' noted that the Vmain dilerence between the Fig. 2 and Fig. 1 embodiments resides in the substitution of resistor v 18 for lamp 18.

The operation of Fig. 2 circuit will now be described. When the switch 11 is closed, condenser 21 charges through resistor 12 and igniter 2010 a final voltage approaching that of that portion of source 10 between tap 19 and its positive terminal. The charging current .is relatively small, however, and does not ignite the igniter.

The grid initially has a potential, negative with re- Y spect to the cathode, determined by the setting of adjustable tap 19 on source 10 and substantially the same as that of the negative terminal of the source with ref spect to tap 19. Both plates of condenser 16 initially are at the potential of the negative side Vofl battery 10.

As condenser 16 is charged through resistor 17, resistors y 18', 17, and 15 act -as Va voltage divider and slowly reduce the negative bias at point 23 as the voltage across condenser 16 increases as a result of charging from source 10. The circuits 'are so adjusted that the 'time constant of condenser charging circuit 10, 17, 16, is short compared to the time constant of condenser discharge circuit 16, 18, 15. Thus, tube 14 remains nonconductive until condenser 16 becomes charged. Eventually the amount by which the negative grid bias is reduced approximates ll of the source voltage and the resulting net voltage applied to the input circuit of the Thyratron is equal approximately to the `algebraic sum of $41 Vof the source voltage and the voltage between tap 19 and the negative terminal of source 10. The circuits are so adjusted that the Thyratron fires when condenser-16 has become charged. It'will be understood that condenser 16 charges at a rate slow with respect to the charg- By proper setting of adjustable tap 19, the instant of tiring ,Y

tiring occurs, condenser 21, which has by this time become suciently charged, sendsharelatively heavy; discharge current through the Thyratronfand the igniter,

igniting the latter. While the voltage across condenser Y 16 increases by any given amount, the bias of the Thyra- Yent on the slow charging of a condenser through a high resistance audits rapid discharge through a partly gaseous g of the Thyratron may thus be controlled. When-such path, coupled with the control of the conductivity of that path by another circuit also including a condenser and a resistor. They diler primarily in that the Fig. 1 embodiment depends upon an abrupt reduction of grid bias due to a discharge in a neon lamp to effect firing, while in the Fig. 2 embodiment the grid bias gradually becomes less negative.

While there havel beenshown andV described what are at present considered to be the preferred embodiments of thepresent invention, it will be obvious to those skilled in the art that various changesV and modifications may be -made therein without departing from the true spirit of l the invention and it is, accordingly, intended in the appended claims to cover allgsuch changes and modifications as fall within the proper scope of the invention and without that of the priorart.

We claim: Y

1. A fuze for an ordnance missile comprising, a work circuit including a first capacitor and a squib connected in series, a gaseous discharge device having an anode,

Va cathode and a control electrode, said anode and said cathode being connected across said work circuit to form a parallel electrical circuit therewith, a source of electrical energy. providing positive and negative potentials with respect to said cathode, a iirst resistor for connecting said source of positive potential to said anode, an input circuit including a second resistor and a second capacitor connected in series, the remaining termination of said second resistor being connected to said source of positive potential and the remaining termination of said second capacitor being connected to said source of negative potential to provide a `.time varying potential across said second capacitor, means for applying said time varying potential to said control electrodeand means, operative on setback uponring of the missile for initiating the action of said control circuit, wherebywupon the expiration -of a l pre-selected time after setback, said discharge'device isV rendered conductive thereby causing a4 surge of current to ow through said squib to produce detonation of said fuze.

2. An arrangement as set forth Yin claim l, wherein said means for applying said time varying potential to said control electrode comprises a voltage dividerrconnected across said second capacitor and including a nonlinear impedance and a third resistor connected in series, the remaining termination of said Vthird resistor being connected to said source of negative potential, the remaining termination of said non-linear impedance being connected to the junction of said second resistor and said second capacitor, and the junction of said non-linear impedance and said third resistor being connected to said control electrode.

3. An arrangement'as set forth in claim "l, wherein said means for applyingsaid time varying potential to said control electrode comprises a voltage divider including a third resistor and a fourth resistor connected in series with'the remaining terminations of said third andV fourth resistors connectedacrossy said second capacitor,

and a connection between an intermediate point along said voltage divider and said control electrode.

References Cited in thevile of this patent UNITED STATES PATENTS Y 2,164,538 Meier Julyr 4,

2,172,050 Mayberry Sept. 5, 1939/ 2,331,317 Germeshausen Oct. l2, 1943 2,331,771 `Germeshausen Oct. 12, 1943 2,403,567 Wales July 9, `1946 2,404,553 Wales July 23, 1946 2,514,434 Windes Iulyll, 1950 FOREIGN PATENTS 549,998 Great Britain Dec. 1,7, 1942 

